The present invention relates generally to the field of semiconductor device manufacturing, and more particularly, to an apparatus and method of coarsely aligning a packaged semiconductor device.
Semiconductor devices are typically fabricated on thin wafers of silicon. Several die are produced on each wafer, with each die representing a single semiconductor device. Each die on a wafer is tested for gross functionality, and sorted according to whether the die passes or fails the gross functionality test. After being sorted according to gross functionality, the wafers are cut using a wafer saw and the individual die are separated. The die determined to be non-functional are scrapped. The functional die are packaged and further tested to ensure that each packaged device satisfies a minimum level of performance. The reliability of the packaged devices are tested by further subjecting them to a xe2x80x9cburn-inxe2x80x9d period where the devices are tested at an elevated voltage and elevated temperature for a period of time.
Functional devices may be permanently packaged by encapsulating the die in a plastic package, or temporarily packaged by mounting the die in a ceramic package. Packaging the functional devices facilitates handling of the device and also protects the die from damage during performance and reliability testing. The packaged devices are typically stored in carrying trays having recesses into which the device is placed. The packaged devices are transported from one test station to another in the carrying trays.
Automated device handlers are used during the testing and burn-in phase to facilitate handling of the packaged devices. The handlers automatically unload the packaged devices from the carrying trays, and transport and position the devices for testing by a test unit. The handler then reloads the packaged devices into a carrying tray when testing is complete.
When unloading a packaged device from a carrying tray, the handler may need to align the packaged device prior to placing it into a handler boat. Although the carrying tray provides some alignment, it may not be within the precision required for placement into the handler boat without damaging the packaged device. A mechanical structure known as a precisor is used to coarsely align the packaged device. The packaged device is placed into a recess in the precisor for alignment. The packaged device is then removed from the precisor and placed into the handler boat to be transported within the automated device handler to a handler chuck.
The handler chuck receives the packaged device from the handler boat and positions it to come in contact with a contactor. The contactor has a series of conductors that electrically contact the leads of the packaged device. A tester unit connected to the contactor applies a series of signals to the packaged device through the series of conductors in order to test the functionality of the device. Before the handler chuck puts the packaged device into contact with the contactor, the packaged device must be correctly oriented. Although the contactor is designed to receive a packaged device that is not precisely oriented to the contactor, the packaged device must still be coarsely aligned within a certain measure. An incorrectly oriented packaged device may be damaged when forced into contact with the contactor, or incorrectly tested when the leads of the packaged device contact the incorrect conductors because the device is misaligned with respect to the contactor.
After testing is complete, the packaged device is pulled away from the contactor by the handler chuck and returned to the handler boat. The packaged device is transported by the handler boat to be reloaded into a carrying tray.
Shown in FIG. 1 is an example of a conventional fixed alignment tooling 2 used for coarsely aligning a packaged device 3. The fixed alignment tooling 2 may be used in the singulated device handling applications described previously, that is, for a precisor, or handler boat or chuck. The fixed tooling 2 includes a base 4 having a recess 6 defined by chamfered surfaces 8a-d. The packaged device 3 is coarsely aligned by the chamfered surfaces when placed into the recess 6 and rests on either on the package balls or on the package substrate if relief for the ball pattern is provided. The chamfered surfaces 8a-d also guide the packaged device 3 into the recess 6 when slightly skewed and facilitate positioning of the packaged device 3 within the recess 6. The coarsely aligned packaged device 3 can then be transported or transferred within the automatic handler positioned with the proper alignment.
It can be seen that the fixed tooling 2 works only for a packaged device having a particular shape and size. The fixed alignment tooling 2 requires replacement when the shape or size of the packaged device changes. The costs involved with changing the fixed tooling 2 is considerable when refitting an entire test area. For example, the fixed tooling of the precisor, handler boats and chucks would need to be retrofitted to accommodate a packaged device having a new shape or size. Fortunately, the need to change the fixed tooling 2 arises infrequently because the shape and size of current device package types, for example, SOJ, ZIP, or TSOP packages, are not affected when the size of the die encapsulated within the package is decreased.
The die size of a semiconductor device is typically shrunk in an effort to increase the number of die fabricated on each wafer, and consequently, increase the number of die potentially yielded by each wafer. Die shrinks occur throughout the lifetime of a semiconductor device. The shape and size of the package is generally unaffected by a die shrink because each succeeding generation of smaller die are simply encapsulated in the same sized package as their larger progenitor. Thus, the infrequency of changing the fixed tooling 2 allows for the associated costs to be amortized over a relatively long period of time. However, as the shape or size of device packages change more frequently during the lifetime of a device, the relative costs will increase. Therefore, it can be appreciated that there is a need for an apparatus that can coarsely align packaged semiconductor devices and minimize the costs associated with changing the fixed toolings whenever the size of the device package changes.
The present invention is directed to an apparatus and method for positioning packaged semiconductor devices having different rectangular shapes and sizes. A positioning apparatus includes an adjustable alignment guide that may be positioned along a first axis to partially define a recess into which the packaged semiconductor devices are placed during positioning. The adjustable alignment guide may be an alignment surface against which the integrated circuit rests when placed into the recess partially defined by the alignment surface. The adjustable alignment guide may be slidably attached to a base, and moved by sliding the guide to the appropriate position according to the shape and size of the packaged semiconductor device to be positioned. The positioning apparatus may also include additional adjustable alignment guides that may be positioned along the first or a second axis to further define the recess into which the packaged semiconductor device is to placed during positioning.